This has been so vague as to make no sense until now. I think I have finally worked out what you have.
It seems as though your machine is intended for grid tie with the windy boy inverter but the dump controller is a backup to hold the volts down to a safe level for the inverter, it will not normally be in operation but in high winds it will clip the peak voltage to prevent damage to the inverter.
I have no idea if your dump load is capable of dissipating the full power of the turbine, I suspect not, what would be the point if the intention is to feed power to the grid.
You may find that the resistors and just slammed in as a peak limiter with the intention of driving the blades into stall to hold the peak level within range of the inverter.
Unless you find out for sure how this is all intended to operate then You are on tricky ground.
I suspect that under normal conditions you could run the inverter but you would have to watch it in high wind and with no furling you may get out of control.
You will not hurt the turbine to run it for heating but you may wreck your dump load if it wasn't designed for that.
With this new equipment and your seemingly total lack of knowledge of what you have, I think you would be foolish to mess about with the dump load. If you have enough knowledge you could build a controller for water heating using immersion heaters, but if you have that knowledge you could probably build a voltage clipper for the inverter, but having spent money on one that seems crazy.
Flux